Yellow fever mosquitoes spread fear of deadly viruses in Los Angeles

Ebola may not be the only cause of fear to arrive in the US recently. Yellow fever mosquitoes ‒ which can transmit dengue, chikungunya and yellow fever itself ‒ have been found in the Los Angeles region, officials announced Wednesday.

These mosquitoes can spread the three deadly tropical viruses to
humans through their bites. They were found Oct. 7 and 8 in
Commerce and Pico Rivera, respectively, according to the Greater
Los Angeles County Vector Control District (GLACVCD) and San
Gabriel Valley Mosquito & Vector Control District (SGVMVCD).

Like Ebola, yellow fever is an acute viral hemorrhagic
disease. However, instead of being spread by bodily fluids, it is
carried in the salivary glands of a mosquito. The ‘yellow’ in the
name refers to the jaundice that affects some patients, according
to the World Health Organization. The virus is endemic in
tropical areas of Africa and Latin America, and there are an
estimated 200 000 cases of yellow fever, causing 30 000 deaths,
worldwide each year, with 90 percent occurring in Africa.

Dengue virus is a leading cause of illness and death in the
tropics and subtropics, mostly in urban and semi-urban areas,
with as many as 400 million people infected yearly, the US
Centers for Disease Control and Prevention reported. The
infection causes flu-like illness, and occasionally develops into
a potentially lethal complication called severe dengue (also
known as Dengue Haemorrhagic Fever), according to the WHO.

Chikungunya is a viral disease that causes
fever and severe joint pain. Other symptoms include muscle pain,
headache, nausea, fatigue and rash, similar to dengue, which can
cause misdiagnosis in areas where both viruses are common. Since
2004, chikungunya fever has reached epidemic proportions, with
considerable morbidity and suffering, the WHO said. Most patients
recover fully, but in some cases joint pain may persist for
several months, or even years. Occasional cases of eye,
neurological and heart complications have been reported, as well
as gastrointestinal complaints. Chikungunya occurs in Africa,
Asia and the Indian subcontinent.

The first reported case of chikungunyain the US was reported July 17 in
Florida. “This newly reported case represents the first time
that mosquitoes in the continental United States are thought to
have spread the virus to a non-traveler,” the CDC announced.

Now the viruses spread by the yellow fever mosquito could
potentially arrive clear across the country from Florida.

"While these debilitating viruses, so far, aren't locally
transmitted in LA County, the mosquitoes that can transmit them
are now here," Susanne Kluh, director of
scientific-technical services, said in a statement. "Infected
travelers can bring these viruses to Los Angeles County."

“This is the latest in a series of identified mosquito
introductions into the southland,” Levy Sun, the GLACVCD’s
public information officer said in the district’s joint statement
with SGVMVCD.

The Aedes aegypti species, better known as the yellow fever
mosquito, has black and white stripes and grows to about a
quarter-inch in size. It is primarily a forest species that has
become adapted to rural, suburban and urban human environments.
In recent decades Aedes albopictus has spread from Asia to
Africa, the Americas and Europe, notably aided by the
international trade in used tires as mosquitoes deposit their
eggs in tires containing rainwater, the WHO said.

The Aedes albopictus species ‒ the Asian tiger mosquito ‒ is a
native of Southeast Asia, and was first identified in El Monte
and South El Monte, Calif. in September 2011. Since then, this
mosquito has spread to 10 neighboring cities despite aggressive
measures to eradicate the population, the vector control
districts said. It also spreads dengue, chikungunya and yellow
fever.

The Australian backyard mosquito (Aedes notoscriptus), a native
of Australia, was found in two neighborhoods in Montebello and
Monterey Park this summer. It can transmit canine heartworm and
is the primary transmitter of the Barmah Forest and Ross River
viruses in Oz.

All three mosquitoes are aggressive day-biting mosquitoes that
thrive in urban environments because they prefer to lay eggs in
small man-made containers that hold water.

The two vector control districts are working closely with the Los
Angeles County Department of Public Health, which tracks imported
human diseases.

Officials are asking residents to report any sightings of the
small, black-and-white mosquitoes, especially if someone is
bitten during the day. They are also requesting people dump and
drain all stagnant water, and to “thoroughly scrub”
places susceptible to standing water on a weekly basis.

The districts have not determined how the yellow fever mosquito
or either of the other disease-transmitting biters arrived in
California. Along with imported tires, plants are typically to
blame, officials noted. The bugs can also travel via planes,
ships and other vehicles.